Turn signal self cancelling unit

Hi Guys.
can anybody tell me how to check if I have a problem with my turn signal self cancelling unit on my 1982 KZ750 Ltd. the turn signal does not automatically turn off. I’m guessing it is either the solenoid in the switch or maybe the signal self cancelling unit. What would I need to check with my multimeter to determine if the unit is bad. I’m guessing it is permanently on, which is why I have to manually switch the turn signal off and move it back to centre. 
As always any advice is gratefully received.

Thanks in advance
J

It would be helpful to members here if you would include the year and exact model kz you have in the signature line of your message. That way, readers will be able to give specific advice, and you will not have to type it every time you have a question.
Also, there will be a trouble shooting section on that system in the factory service manual. Many of them are  available for free, in digital format, here at KZRider. Click on the Articles menu to find them.

There's a good Kawasaki factory service manual pdf available for the 750-4 chain drive models.  Yellow-gold cover w color wiring diagrams.
The turn signal cancelling unit troubleshooting info is the the 1981 supplement of the FSM. pages 276-278.

Ok, thanks for that. I’ll remember to put make model and year in the title block for future issues.
thanks for pointing out my error.

Here is the manual. Select the GPZ750, 4th from the top

www.kzrider.com/service-manuals

Not familiar with that particular model.  Are these the typical early Kawasaki 'mechanical' (as opposed to electronic - a much better design) self cancelling units with a solenoid in the switch cluster?  Some models have a second switch to disable the self cancelling feature - check that first if your model has one.  If it's the mechanical switch type, the internals get gummed up and 'stuck'.  The guts can be disassembled, cleaned and lubricated (but there are parts that will want to go AWOL).  Before fully dissembling, I'd try opening the switch cluster and clean what you can with a Q-tip and some light solvent then re-lube very lightly.

 

No eBay APP ID and/or Cert ID defined in Kunena configurationI think this is the manual you want, manual page 276 (pdf document page 270):   kzrider.com/filebase/download/17-kz750/1...e1-h1-service-manual

I have worked on a similar system on a 1978 Z1R.  I know the early 80s 550s had the nearly same setup, and I'm guessing the 750 was similar.

Here are the three pieces:
(1)
There is a solenoid in the left-hand control block.  This pulls in a pin and physically releases the turns signal switch allowing it to center.  This solenoid is protected by a thermal fuse.  If the solenoid coils get too hot, the fuse opens.  It's a one-time fuse.  This happened to my bike, and I had to remove the solenoid and solder in a new fuse. 
This is easy to check with an ohm meter.  Find the two wires that go to the solenoid.  If they measure some small number (less than 100 ohm?) it's probably ok.  If it's very large (>100000 ohms) you probably have a bad fuse.  The manual says to put 12V on the solenoid (briefly!) to test that it's working.  I would do this after you measure the resistance of the solenoid coil with an ohm meter.

Also, if the solenoid is bad, your control box is also probably bad.  A failed box can overheat the solenoid.

There is also a switch in left control block to enable the system.  You'll need to trace the harness to make sure the switch is working correctly.

(2)
There is a sensor in-line with the speedometer cable on the Z1R.  Based on the KZ750 manual, this device was moved inside the speedo housing.  It's a simple magnet and reed switch.  The sensor has just two wires.  If you disconnect the speedo cable from the front axle and rotate the cable, you should see the switch open and close several times per revolution.  Again, find the wires for this sensor and connect an ohm meter.  You should see the resistance change from near zero to near infinity as you turn the cable.

(3)
The final piece is the control box.  This is hard to test, and impossible to open (the electronics box is filled with epoxy).  If everything else seems good, the box is probably bad.  On my Z1R the box had a big melted hole in the back of it.  I replaced the box with a different one from Ebay and it worked until the connections got a dirty.  

There are several different versions of this box with different connectors.  My Z1R has a different set of connectors than the 550 LTD.  I can't tell from the Partzilla diagrams, but your bike might have one like this?



 

Thanks so much for this. Several great things to check.
wow.....would be lost without this forum.

I sort of mentioned it in passing, but it could also just be a poor connection in one of the harness connector pins, or an issue with the harness wires.  My bike was working fine for a while, but has become intermittent.  I'm assuming I have a bad connection somewhere.  

If the sensor, solenoid, and enable switch all test ok, I'd look at all of the connectors that the relevant signals pass through.  Maybe clean the pins with some contact cleaner.

If that looks good, then see if you can pick up a replacement control box cheap on eBay.  They do show up for cheap, but you might have to wait and watch.